1 Fix ext4_ext_find_extent() to already pre-allocate ext4_ext_path[]
2 array of the max depth instead of current depth.
3 This will avoid racy cases of concurrent ext_depth() growth in
4 current and unsafe implementation with ext4_ext_path[] array
5 re-[sizing,allocation], even with more recent and related patches
6 that will be integrated in more recent Kernels.
8 Index: linux-2.6.32-504.el6.x86_64/fs/ext4/ext4.h
9 ===================================================================
10 --- linux-2.6.32-504.el6.x86_64.orig/fs/ext4/ext4.h
11 +++ linux-2.6.32-504.el6.x86_64/fs/ext4/ext4.h
13 unsigned long s_ext_extents;
16 + /* maximum possible extents tree depth, to be computed at mount time */
17 + unsigned int s_max_ext_tree_depth;
19 /* for buddy allocator */
20 struct ext4_group_info ***s_group_info;
21 struct inode *s_buddy_cache;
22 Index: linux-2.6.32-504.el6.x86_64/fs/ext4/super.c
23 ===================================================================
24 --- linux-2.6.32-504.el6.x86_64.orig/fs/ext4/super.c
25 +++ linux-2.6.32-504.el6.x86_64/fs/ext4/super.c
27 if (ext4_multi_mount_protect(sb, le64_to_cpu(es->s_mmp_block)))
30 + ext4_ext_init(sb); /* needed before using extent-mapped journal */
33 * The first inode we look at is the journal inode. Don't try
34 * root first: it may be modified in the journal!
40 err = ext4_mb_init(sb);
42 ext4_msg(sb, KERN_ERR, "failed to initialize mballoc (%d)",
43 Index: linux-2.6.32-504.el6.x86_64/fs/ext4/extents.c
44 ===================================================================
45 --- linux-2.6.32-504.el6.x86_64.orig/fs/ext4/extents.c
46 +++ linux-2.6.32-504.el6.x86_64/fs/ext4/extents.c
49 /* account possible depth increase */
51 - path = kzalloc(sizeof(struct ext4_ext_path) * (depth + 2),
53 + path = kzalloc(sizeof(struct ext4_ext_path) *
54 + (EXT4_SB(inode->i_sb)->s_max_ext_tree_depth + 1),
57 return ERR_PTR(-ENOMEM);
59 @@ -1915,11 +1916,8 @@
60 /* find extent for this block */
61 down_read(&EXT4_I(inode)->i_data_sem);
63 - if (path && ext_depth(inode) != depth) {
64 - /* depth was changed. we have to realloc path */
68 + /* path of max possible depth will be allocated during
69 + * first pass, so its space can be re-used for each loop */
71 path = ext4_ext_find_extent(inode, block, path);
75 le16_to_cpu(path[k].p_hdr->eh_entries)+1;
77 - path = kzalloc(sizeof(struct ext4_ext_path) * (depth + 1),
79 + path = kzalloc(sizeof(struct ext4_ext_path) *
80 + (EXT4_SB(inode->i_sb)->s_max_ext_tree_depth + 1),
83 ext4_journal_stop(handle);
85 @@ -3048,13 +3034,14 @@
87 void ext4_ext_init(struct super_block *sb)
89 + ext4_fsblk_t maxblocks;
92 * possible initialization would be here
95 if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_EXTENTS)) {
96 -#if defined(AGGRESSIVE_TEST) || defined(CHECK_BINSEARCH) || defined(EXTENTS_STATS)
97 - printk(KERN_INFO "EXT4-fs: file extents enabled"
98 + printk(KERN_INFO "EXT4-fs (%s): file extents enabled"
99 #ifdef AGGRESSIVE_TEST
102 @@ -3064,8 +3051,31 @@
109 + EXT4_SB(sb)->s_max_ext_tree_depth = 1;
111 + maxblocks = sb->s_maxbytes / sb->s_blocksize;
113 + /* 1st/root level/node of extents tree stands in i_data and
114 + * entries stored in tree nodes can be of type ext4_extent
115 + * (leaf node) or ext4_extent_idx (internal node) */
116 + maxblocks /= (sizeof(((struct ext4_inode_info *)0x0)->i_data) -
117 + sizeof(struct ext4_extent_header)) /
118 + max(sizeof(struct ext4_extent),
119 + sizeof(struct ext4_extent_idx));
121 + /* compute maximum extents tree depth for a fully populated
122 + * file of max size made of only minimal/1-block extents */
123 + while (maxblocks > 0) {
124 + maxblocks /= (sb->s_blocksize -
125 + sizeof(struct ext4_extent_header)) /
126 + max(sizeof(struct ext4_extent),
127 + sizeof(struct ext4_extent_idx));
128 + EXT4_SB(sb)->s_max_ext_tree_depth++;
131 + printk(", maximum tree depth=%u\n",
132 + EXT4_SB(sb)->s_max_ext_tree_depth);
134 spin_lock_init(&EXT4_SB(sb)->s_ext_stats_lock);
135 EXT4_SB(sb)->s_ext_min = 1 << 30;